title: Wall shear stress distribution at the carotid bifurcation: influence of eversion carotid endarterectomy.
abstract: OBJECTIVE
  To test the feasibility of four-dimensional (4D) flow MRI to quantify the systolic wall shear stress (WSSsystole) and oscillatory shear index (OSI) in high-grade internal carotid artery (ICA) stenosis before and after endarterectomy (CEA).
  
  
  METHODS
  Twenty patients with ≥60 % ICA stenosis were prospectively and consequently included. Four-dimensional flow MRI was used to measure individual time-resolved 3D blood flow velocities. Segmental WSSsystole and OSI were derived at eight wall segments in analysis planes positioned along the ICA, common (CCA) and external carotid artery (ECA).
  
  
  RESULTS
  Regional WSSsystole of all patients decreased after CEA (P < 0.05). Changes were most prominent at the ICA bulb but remained unchanged in the CCA and ECA. OSI was significantly lower after CEA in the lateral vessel walls (P < 0.05). For analysis planes at the stenosis in- and outlet, a reduction of mean WSSsystole by 32 % and 52 % (P < 0.001) and OSI distal to the stenosis (40 %, P = 0.01) was found after CEA.
  
  
  CONCLUSIONS
  Our findings show the potential of in vivo 4D flow MRI to quantify haemodynamic changes in wall shear stress even in patients with complex flow conditions.
authors.affiliation: Department of Neurology, University Hospital Freiburg, Breisacher Strasse 64, 79106, Freiburg, Germany, andreas.harloff@uniklinik-freiburg.de.
authors.forename: A
authors.initials: A
authors.lastname: Harloff
authors.forename: S
authors.initials: S
authors.lastname: Berg
authors.forename: A J
authors.initials: AJ
authors.lastname: Barker
authors.forename: J
authors.initials: J
authors.lastname: Schöllhorn
authors.forename: M
authors.initials: M
authors.lastname: Schumacher
authors.forename: C
authors.initials: C
authors.lastname: Weiller
authors.forename: M
authors.initials: M
authors.lastname: Markl
mesh_terms: D000368:Aged; D001783:Blood Flow Velocity; D002343:Carotid Artery, Internal / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D016893:Carotid Stenosis / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery*; D016894:Endarterectomy, Carotid; D005240:Feasibility Studies; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D011446:Prospective Studies; D013314:Stress, Mechanical; D013599:Systole